1. Field of the Invention
The present invention relates to a resin composition for underlayer film formation, a layered product, a method for forming a pattern and a process for producing a device. More specifically, the present invention relates to a resin composition for underlayer film formation which is used for improving adhesiveness between a photocurable composition for imprints and a base material. More particularly, the present invention relates to a resin composition for underlayer film formation which is used for patterning through photoirradiation, and which is used in manufacturing of semiconductor integrated circuits, flat screens, microelectromechanical systems (MEMS), sensor devices, optical discs, magnetic recording media such as high-density memory disks, optical members such as diffraction gratings and relief holograms, optical films or polarizing elements for production of nanodevices, optical devices, and flat panel displays, thin-film transistors in liquid-crystal displays, organic transistors, color filters, overcoat layers, pillar materials, rib materials for liquid crystal alignment, microlens arrays, immunoassay chips, DNA separation chips, microreactors, nanobio devices, optical waveguides, optical filters, photonic liquid crystals, and molds for imprints.
2. Description of the Related Art
Imprint technology is a development advanced from embossing technology well known in the art of optical disc production, which includes pressing a mold prototype with a concave-convex pattern formed on its surface (this is generally referred to as “mold”, “stamper” or “template”) against a resist to thereby accurately transfer a fine pattern onto the resist through mechanical deformation of the resist. In this technology, when a mold is prepared once, microstructures such as nanostructures can then be easily and repeatedly molded, and therefore, this is economical, and in addition, harmful wastes and discharges from this nanotechnology are reduced. Accordingly, in recent years, it has been anticipated that this will be applied to various technical fields.
Two methods of imprint technology have been proposed; one is a thermal imprint method using a thermoplastic resin as the material to be worked (for example, see S. Chou et al.: Appl. Phys. Lett. Vol. 67, 3114(1995)), and the other is an imprint method using a curable composition (for example, see M. Colburn et al: Proc. SPIE, Vol. 3676, 379 (1999)). In the thermal imprint method, a mold is pressed against a thermoplastic resin heated up to a temperature not lower than the glass transition temperature thereof, then the thermoplastic resin is cooled to a temperature not higher than the glass transition temperature thereof and thereafter the mold is released to thereby transfer the microstructure of the mold onto the resin on a substrate. This method is very simple and convenient, and is also applicable to a variety of resin materials and glass materials.
On the other hand, imprinting is a method of transferring a fine pattern onto a photo-cured material, by allowing a curable composition to photo-cure under photoirradiation through a light transmissive mold or a light transmissive substrate, and then separating the mold. This method is applicable to the field of high-precision processing for forming ultrafine patterns such as fabrication of semiconductor integrated circuits, since the imprinting may be implemented at room temperature. In recent years, new trends in development of nano-casting based on a combination of advantages of both, and reversal imprinting capable of creating a three-dimensional laminated structure have been reported.
In such an imprint method, the following applications have been proposed.
A first application relates to a geometry (pattern) itself obtained by molding being functionalized so as to be used as a nanotechnology component, or a structural member, examples of which include a variety of micro- or nano-optical components, high-density recording media, optical films, and structural members of flat panel displays.
A second application relates to the building-up of a laminated structure by simultaneous casting of microstructures and nanostructures or by simple layer-to-layer alignment, and use of the laminated structure for manufacturing a Micro-Total Analysis System (μ-TAS) or a biochip.
A third application relates to use of the thus-formed pattern as a mask through which a substrate is processed by a method such as etching. By virtue of high precision alignment and a high degree of integration, this technique can replace a conventional lithographic technique in fabrication of high-density semiconductor integrated circuits, fabrication of transistors in liquid crystal displays, and magnetic processing for next-generation hard disks referred to as patterned media. Efforts to use imprinting practically in these applications have recently become active.
With progress of activities in imprinting, adhesiveness between the substrate and the photocurable composition for imprints has come to be a problem. In imprinting, the photocurable composition for imprints is applied over the surface of the substrate, the photocurable composition for imprints is allowed to cure under photoirradiation, in a state of the surface of the substrate being in contact with a mold, and then the mold is separated. In the step of separating the mold, there may be a case where the cured product is separated from the substrate and unfortunately adheres to the mold. This is thought to be because the adhesiveness between the substrate and the cured material is lower than the adhesiveness between the mold and the cured material. As a solution to this problem, a resin composition for underlayer film formation for improving the adhesiveness between the substrate and the cured material has been studied (JP2009-503139A, JP2013-093552A, and JP2014-024322A).